city. Westwardly, beyond the hill of Chapultepec, whose southern side and feet are surrounded by a dense grove of cypresses, and on a rising ground within the military works designed to strengthen the castle, was the Molino del Rey, or King's Mill, which was represented to be a cannon foundry to which large quantities of church bells had been sent to be cast into guns. Still further west, but near the Molino or Mill, was the fortified Casa Mata, containing a large deposit of powder.
These,—together with the strong citadel, lying near the garita of Belen in the south-western corner of the city,—were the principal external defences still remaining beyond the immediate limits of the capital. The city itself stands on a slight swell between lake Tezcoco and the western edge of the valley, and, throughout its greater extent, is girdled by a ditch or navigable canal extremely difficult to bridge in the face of an enemy, which serves the Mexicans not only as a military defence but for drainage and protection of their customs. Each of the eight strong city gates were protected by works of various character and merit. Outside and within the cross fires of these gates there were other obstacles scarcely less formidable towards the south. The main approaches to the city across the flat lands of the basin are raised on causeways flanked by wide and deep ditches designed for their protection and drainage. These causeways, as well as the minor cross roads which are similarly built, were cut in many places and had their bridges destroyed so as to impede the American's advance and to form an entangling net work; while the adjacent meadows were in this rainy season either filled with water in many places or liable to be immediately flooded by a tropical storm.
With these fields for his theatre of action, and these defences still in front of him, it was an important and responsible question, whether General Scott should attack Mexico on the west or on the south.
There can be hardly a doubt that the capture of the hill and castle of Chapultepec, before assaulting the city, was imperatively demanded by